1. Field of the Invention
This invention relates to subsurface irrigation systems, and more particularly, to a subsurface water irrigation apparatus and method, the irrigation apparatus including a unique diffuser system for uniformly distributing the water while simultaneously inhibiting root infiltration into the water distribution apparatus.
2. The Prior Art
Subsurface watering systems are known in the art and incorporate various devices for distributing the water. A primary reason for using a subsurface watering system is that it provides substantial savings in the quantity of water used. Pumping costs are also less in the event a pump is required as compared to the pumping costs incurred when pumping is necessary to supply sufficient pressure in order to operate a conventional sprinkling system. The conventional sprinkling system for lawn and landscape irrigation is usually permanently installed and involves a network of underground pipes to supply the irrigation water to above-ground sprinkler heads spaced throughout the area to be watered. A series of valves control selected portions of the irrigation network and can be either manually controlled or operated by timer devices. Although such a permanent sprinkler system is much more convenient than a manually positioned sprinkler system there are a number of problems associated with these types of sprinkler system.
Water consumption is perhaps the most serious problem since a very high percentage of the sprinkled water is lost to evaporation, particularly during hot, windy weather conditions. Further many sprinkler systems deliver the water at a rate that exceeds the ability of the soil to absorb the water with the result that there is excessive runoff and/or the creation of swampy areas. Both of these conditions contribute to significant water wastage. Additionally, sprinkler systems are always designed so that the spray from each sprinkler head overlaps the spray from adjacent sprinkler heads. Conventionally, this overlap is in the range of about 60% which further exacerbates the runoff problem.
Another problem with conventional sprinkler systems results from overspray that strikes automobiles, buildings, windows, and the like, particularly on windy days. This problem is particularly acute in arid regions of the country since the water in these regions generally contains relatively high concentrations of dissolved salts such as calcium carbonate. The result is that these salts are deposited on the adjacent surfaces where it creates an unsightly deposit when the water evaporates. It is a common sight in these regions to see bricks, windows, automobiles, and the like stained by these unsightly deposits.
Above-ground sprinkler systems also restrict usage of the lawn area watered thereby both during watering and for a period of time thereafter until the grass has become sufficiently dry. Accordingly, it is customary to water golf courses, for example, at night so that the grass will be sufficiently dry for play the next morning. However, this practice exacerbates another problem in that it makes the grass more susceptible to attack by fungi such as mold, moss, etc.
Another problem with above-ground sprinkler systems is that the sprinklers themselves are easily damaged by lawn care equipment, golf carts, etc. A further problem is that many injuries are caused by inadvertent contact with the sprinkler during play or merely by accidently tripping over them.
In the area of water conservation, it is neither practicable nor economically feasible to use what is euphemistically referred to as "grey water" in an above-ground sprinkling system. This arises from the aesthetics of using grey water due to sanitation, odors, etc., plus the added expense of the necessary pumping systems to develop sufficient pressure to render the grey water sprinkler system operable.
Various underground irrigation systems are known in the art. As the name implies, these systems are designed to deliver the water to distribution outlets spaced at intervals along the underground tubing. One patent, for example, (U.S. Pat. No. 3,479,825; Hellstrom) discloses a subsurface irrigational system wherein an artificial barrier is buried a substantial distance below the surface of the soil in order to create an artificial water table below the roots of the crops growing in the soil. Water is introduced into the soil through buried pipes or through deep ditches in order to cause the water to migrate laterally throughout the soil. The barrier prevents the water from disappearing into the earth.
Reese (U.S. Pat. No. 4,060,991) discloses a subsurface irrigation system for plants specifically designed to eliminate problem of roots fouling the water distribution system. An underground, vented chamber includes a float valve mechanism to regulate the quantity of water in the chamber. A pipe carries water from the chamber to a moisture pit. Both the pipe and the moisture pit are filled with sand to provide a capillary path for the water while serving as a root barrier.
Brandt (U.S. Pat. No. 4,065,926) discloses a subterranean irrigation system wherein a coarse screen or grid of flexible material having internal interconnecting passages for the flow of water. The grid is buried underneath the area to be watered. Orifices are distributed along the interconnecting passages to release the water by gravity feed from a source or reservoir.
Funkhouser, Jr. (U.S. Pat. No. 4,832,526) discloses an underground watering system wherein a plurality of equally spaced, shallow water reservoir trenches are prepared. The trenches are formed with rounded surfaces and are lined with a waterproof liner. a water distribution pipe is laid in each trench and the trenches are filled with a fine stone aggregate. A water permeable fabric is placed across the entire area to be watered. A relatively course layer of aggregate is placed over the water permeable fabric followed by an upper layer of relatively fine aggregate. A sod layer is then placed on top of the fine aggregate where its roots receive moisture drawn up through the various layers by capillary action.
U.S. Pat. No. 5,374,138 teaches a lawn area subsurface irrigation system wherein special conduits spaced at predetermined intervals deliver the water into the soil at the root level. A deflector system is included as part of the conduit to block the downward movement of water in the deflecting area below the conduit.
Each of these prior art references are directed to solving problems associated with above-ground sprinkling systems and subsurface irrigation systems. However, unless the subsurface irrigation system is provided will very elaborate and, therefore, costly shielding systems such as those taught by Reese (U.S. Pat. No. 4,060,991) or Funkhouser, Jr. (U.S. Pat. No. 4,832,526) the orifices by which the water is released into the soil will be highly susceptible to encroachment by roots from the plant. That roots will seek out a source of water and, indeed, grow into the source of water to such an extent as to eventually plug the water conduit is a well known fact. For example, an entire service industry has been created around this phenomena in the area of rotary derooting of sewer lines. Subsurface lawn irrigation systems will clearly encounter the same phenomena although on a smaller scale but with the same consequences, namely, plugged orifices.
It would, therefore, be a significant advancement in the art to provide a subsurface irrigation apparatus having a plurality of water distribution lines each having a plurality of orifices therein for the uniform delivery of water, each orifice being shielded from root encroachment by a unique water diffusion device. It would also be an advancement in the art to mount the conduits and the diffusion devices to a water impervious membrane for ease of fabrication and installation of the subsurface irrigation apparatus. Such a novel apparatus and method is disclosed and claimed herein.